.TH jp2a 1  "September 22, 2024" "version 1.3.0" "USER COMMANDS"
.SH NAME
jp2a \- convert JPEG, PNG and WebP images to ASCII
.SH SYNOPSIS
.B jp2a
[
.I options
] [
.I filename(s) | URL(s)
]
.LP
.SH DESCRIPTION
.B jp2a
will convert JPEG, PNG and WebP images to ASCII characters.  You can specify a mixture of files and URLs.
.SH OPTIONS
.TP
.BI \-
Read JPEG, PNG and WebP image from standard input
.TP
.B \-\-background=light \-\-background=dark
If you don't want to mess with \-\-invert all the time, just use these instead.
If you are using white characters on a black display, then use --background=dark,
and vice versa.
.TP
.B \-b \-\-border
Frame output image in a border
.TP
.BI \-\-chars= ...
Use the given characters when producing the output ASCII image.  Default is "   ...',;:clodxkO0KXNWM".
.TP
.BI \-\-colors
Use truecolor (or ANSI color if truecolor is not supported) for text output and CSS color for HTML output.
.TP
. BI \-\-color\-depth= ...
Use a specific color-depth for terminal output. Valid values are: 4 (for ANSI), 8 (for 256 color
palette) and 24 (for truecolor or 24-bit color).
.TP
.B \-d \-\-debug
Print debugging information when using libcurl to download images from the net.
.TP
.B \-f \-\-term\-fit
Use the largest dimension that makes the image fit in your terminal display.
.TP
.B \-\-term\-height
Use terminal display height and calculate width based on image aspect ratio.
.TP
.B \-\-term\-width
Use terminal display width and calculate height based on image aspect ratio.
.TP
.B \-z \-\-term\-zoom
Use terminal display width and height.
.TP
.B \-c \-\-term\-center
Center image in terminal.
.TP
.B \-\-fill
When used with \-\-html and \-\-color, then color each output character's background color.  For instance,
if you want to use fill-output on a light background, do

jp2a --color --html --html-fill --background=light somefile.jpg --output=dark.html

To do the same on a light background:

jp2a --color --html --html-fill --background=dark somefile.jpg --output=light.html

The default is to have fill disabled.
.TP
.B \-x \-\-flipx
Flip output image horizontally
.TP
.B \-y \-\-flipy
Flip output image vertically
.TP
.BI \-\-height= N
Set output height.  If only --height is specified, then output width will
be calculated according to the source images aspect ratio.
.TP
.B \-h \-\-help
Display a short help text
.TP
.B \-\-grayscale
Converts image to grayscale when using \-\-html or \-\-colors.
.TP
.B \-\-html
Make ASCII output in strict XHTML 1.0. (Will output in HTML for version 2.0.0 and above.)
.TP
.B \-\-htmlls
Make ASCII output in HTML (Living Standard), suitable for viewing with web browsers.
This is useful with big output dimensions, and if you want to check the result with a browser with small font.
.TP
.B \-\-xhtml
Make ASCII output in strict XHTML 1.0.
.TP
.B \-\-html\-fill
Same as \-\-fill.  You should use that option instead.
.TP
.B \-\-html\-no\-bold
Do not use bold text for HTML output.
.TP
.B \-\-html\-raw
Output only the image in HTML codes, leaving out the rest of the webpage, so you can construct
your own. (Will use <br> for version 2.0.0 and above instead of <br/>.)
.TP
.BI \-\-html\-fontsize= N
Set fontsize when using \-\-html output.  Default is 4.
.TP
.BI \-\-html\-title= ...
Set HTML output title.
.TP
.BI \-\-output=...
Write ASCII output to given filename.  To explicitly specify standard output, use \-\-output=\-.
.TP
.B \-i \-\-invert
Invert output image.  If you view a picture with white background, but you are using
a display with light characters on a dark background, you should invert the image.
.TP
.BI \-\-red= ...
.TP
.BI \-\-green= ...
.TP
.BI \-\-blue= ...
When converting from RGB to grayscale, use the given weights to calculate luminance.
The default is red=0.2989, green=0.5866 and blue=0.1145.
.TP
.BI \-\-size= WIDTHxHEIGHT
Set output dimension.
.TP
.B \-v \-\-verbose
Print some verbose information to standard error when reading each JPEG image.
.TP
.BI \-\-width= N
Set output width.  If you only specify the width, the height will be
calculated automatically.
.TP
.B \-V \-\-version
Print program version.
.TP
.B \-\-zoom
Sets output dimensions to your entire terminal window, disregarding source image
aspect ratio.
.TP
.B \-\-edge\-threshold= ...
Specifies an image gradient above which to shade lines and edges with directional glyphs (such as -/|\\).
The right value to pick up the edges nicely will depend on the image but might be around 0.5.
.TP
.B \-\-edges-only
Only draw edges, so that the resulting image is like a line drawing or edge detector. This option should
be used in conjunction with \-\-edge\-threshold so that edges are drawn.
.SH RETURN VALUES
jp2a returns 1 when errors are encountered, zero for no errors.
.SH EXAMPLES
Convert and print imagefile.jpg using ASCII characters in 40 columns and 20 rows:
.PP
.B jp2a
\-\-size=40x20 imagefile.jpg
.PP
Download an image off the net, convert and print:
.PP
.B jp2a
http://www.google.com/intl/en/logos/easter_logo.jpg
.PP
Output picture.jpg and picture2.jpg, each 80x25 characters, using the characters " ...ooxx@@" for output:
.PP
.B jp2a
\-\-size=80x25 --chars=" ...ooxx@@" picture.jpg picture2.jpg
.PP
Output image.jpg using 76 columns, height is automatically calculated from aspect ratio of image.jpg
.PP
cat image.jpg |
.B jp2a
\-\-width=76 \-
.PP
If you use jp2a together with ImageMagick's convert(1) then you can make good use of pipes,
and have ImageMagick do all sorts of image conversions and effects on the source image.  For example:
.PP
.B magick
somefile.gif jpg:\- |
.B jp2a
\- \-\-width=80
.PP
Check out convert(1) options to see what you can do.  Convert can handle almost any image format,
so with this combination you can convert images in e.g. PDF or AVI files to ASCII.
.PP
jp2a uses a very basic scaling algorithm for every image format except WebP. To get better quality, convert an image to WebP to make use of the scaling built into the libwebp library:
.PP
.B cwebp
\-quiet
image.jpg
\-o
\- |
.B jp2a
\-
.PP
Although the default build of jp2a includes automatic downloading of files specified by URLs,
you can explicitly download them by using curl(1) or wget(1), for example:
.PP
.B curl
\-s
http://foo.bar/image.jpg |
.B magick
\- jpg:- |
.B jp2a
\-
.PP
You can pass the \-\-edge\-threshold option to highlight the edges of the image, or add the
\-\-edges\-only option to draw only the edges, to produce a line drawing.
.PP
.B jp2a
\-\-edge\-threshold=0.5 \-\-edges\-only imagefile.jpg
.SH DOWNLOADING IMAGES FROM THE NET
If you have compiled jp2a with libcurl(3), you can download images by specifying URLs:

.B jp2a
https://user:pass@foo.com/bar.jpg

The protocols recognized are ftp, ftps, file, http, https and tftp.

If you need more control of the downloading, you should use curl(1) or wget(1) and jp2a
read the image from standard input.

jp2a uses pipe and fork to download images using libcurl (i.e., no exec or system calls) 
and therefore does not worry about malevolently formatted URLs.
.SH GRAYSCALE CONVERSION
You can extract the red channel by doing this:

.B jp2a
somefile.jpg --red=1.0 --green=0.0 --blue=0.0

This will calculate luminance based on Y = R*1.0 + G*0.0 + B*0.0.  The default
values is to use Y = R*0.2989 + G*0.5866 + B*0.1145.
.SH PROJECT HOMEPAGE
The latest version of jp2a and news is always available from https://github.com/Talinx/jp2a.
.SH SEE ALSO
cjpeg(1), djpeg(1), jpegtran(1), convert(1), cwebp(1)
.SH BUGS
jp2a does not interpolate when resizing (except for WebP images).  If you want better quality, try using cwebp(1)
to convert the image to WebP before using jp2a to get correct scaling.
.PP
Another issue is that jp2a skips some X-pixels along each scanline.  This gives a less
precise output image, and will probably be corrected in future versions.
.SH AUTHOR
Christian Stigen Larsen and Christoph Raitzig

jp2a uses jpeglib to read JPEG files.  jpeglib is made by The Independent JPEG Group (IJG),
who have a page at http://www.ijg.org

jp2a uses libpng to read PNG files.  libpng's homepage: http://libpng.org/pub/png/libpng.html

jp2a uses libwebp to read WebP files.  libwebp's homepage: https://developers.google.com/speed/webp/
.SH LICENSE
jp2a is distributed under the GNU General Public License v2.